1. Field of the Invention
This invention relates to a display device, and more particularly, to a liquid crystal display device.
2. Background of the Related Art
A liquid crystal display device provides the picture display for a video signal by controlling the light transmissivity of a liquid crystal. The gray level of picture changes non-linearly in accordance with the voltage level of a video signal due to so-called gamma characteristic. This is caused by the fact that: (1) the light transmissivity of the liquid crystal does not change linearly in accordance with the voltage level of the video signal, and (2) the gray level of picture does not change linearly in accordance with the light transmissivity of the liquid crystal. Due to this gamma characteristic, the pictures displayed on a liquid crystal display device are deteriorated.
In order to compensate an error in the gray level, the voltage levels of the video signal for the liquid crystal display device are changed at different intervals using gamma compensating voltages. The number of gamma compensating voltage used in the liquid crystal display device is usually about two to twelve, but increases in proportion to the number of gray levels. Such an increase in the number of gamma compensating voltages not only complicates the wiring and circuitry of the liquid crystal display apparatus, but also enlarges a signal distortion due to parasitic capacitance components and the bulk of the liquid crystal display device.
Such problems are further amplified when driving ICs are mounted on the liquid crystal panel. Generally, a liquid crystal display device includes a liquid crystal panel as a picture display element, driving integrated circuits(ICs) for driving the liquid crystal panel, and an electrical signal modulating circuit for supplying signals required for the driving ICs. The driving ICs were previously installed separately from the liquid crystal panel, but recently they have been mounted on the liquid crystal panel. The liquid crystal panel mounted with the driving ICs is generally referred to as xe2x80x9cchips on glassxe2x80x9d(COG). In the COG, the driving ICs are installed on the pad region of the liquid crystal panel.
FIG. 1 illustrates a liquid crystal display device 1 using COG. The liquid crystal display device 1 includes an upper glass substrate 10 and a lower glass substrate 12 that are in opposition to each other. Column driving ICs 14 are linearly installed on the pad region near the upper side edge of the lower glass substrate 12. Row driving ICs 16 are installed serially on the pad region near the left side edge of the lower glass substrate 12. An electrical signal modulation circuit 18 supplies signals required for these column driving ICs 14 and row driving ICs 16. Liquid crystal cells arranged in a matrix configuration and having thin film transistors(TFTs) for switching each current path of the liquid crystal cells are formed between the upper glass substrate 10 and the lower glass substrate 12. The column driving ICs 14 drives drain electrodes of the TFTs, and the row driving ICs 16 drives gate electrodes of the TFTs.
A column data signal wiring CSW, a column timing signal wiring CTW and a gamma compensating signal wiring GCW, all of which are connected to the column driving ICs 14, are formed on the upper side pad region of the lower glass substrate 12. A row timing signal wiring RTW and a row signal wiring RSW connected to the row driving ICs 16 are formed on the left side pad region of the lower glass substrate 12. These column data signal wiring CSW, column timing signal wiring CTW, gamma compensating signal wiring GCW, row timing signal wiring RTW and row signal wiring RSW are connected to the electrical signal modulating circuit 18 by means of a flexible circuit substrate 20. Further, a voltage signal wiring and the like (not shown) are formed in the pad regions of the lower glass substrate 12. This voltage signal wiring is connected via the flexible cable to the electrical signal modulating circuit 18 similar to the other wirings.
The gamma compensating wiring GCW in the above wirings generally consists of seven gamma compensating voltage lines in order to deliver seven gamma compensating voltages applied via the flexible circuit substrate 20 from the electrical signal modulating circuit 18 into the column driving ICs 14. Because the number of these gamma compensating voltages is greater than that of other signals, the number of signal lines included in the gamma compensating signal wiring GCW and the number of intersecting points in the signal lines increase. Hence, the gamma compensating signal wiring GCW occupies a wide area of the pad region. The gamma compensating signal wiring GCW also causes a gamma compensating voltage generator to be provided in the electrical signal modulating circuit 18, thereby complicating the circuit configuration. Furthermore, the gamma compensating signal wiring GCW distorts a signal because it generates parasitic capacitance components between the lines. The drawbacks as described above are more and more deteriorated as the gray level of picture increases.
An object of the present invention is to solve the problems and/or disadvantages of the background art.
Another object of the present invention to minimize the pad margin of a liquid crystal panel.
Another object of the present invention is to minimize the size of a liquid crystal display device.
A further object of the present invention is to simplify the circuit configuration and/or the wiring structure of the liquid crystal display device.
To achieve the present invention in parts or in a whole by a gray level compensating voltage supplying apparatus which includes a main gamma compensating signal line being defined on the liquid crystal panel for delivering a main gamma compensating voltage from the exterior thereof, and at least two conductive patterns being arranged on the liquid crystal panel to be adjacent to the at least two column driving integrated circuits, the at least two conductive patterns each dividing the main gamma compensating voltage from the main gamma compensating signal line into at least two divided voltages and supplying the divided voltages to the adjacent column driving integrated circuits as gamma compensating voltages.
The present invention may be also achieved in parts or in a whole by a gray level compensating voltage supplying apparatus which includes a main gamma compensating signal line being defined on the liquid crystal panel for delivering a main gamma compensating voltage from the exterior thereof, at least two nodes defined on the liquid crystal panel, at least two connectors for cascade-connecting the at least two nodes to the main gamma compensating signal line and for generating divided voltages having different voltage levels on the at least two nodes, and at least three branches for delivering voltages on the at least two nodes and the main gamma compensating signal line into the driving integrated circuit as gamma compensating voltages.
The present invention may be further achieved in parts or in a whole by a liquid crystal display apparatus which includes a main gamma compensating signal line being defined on a liquid crystal panel to receive a main gamma compensating voltage from the exterior thereof, the liquid crystal panel being mounted with a driving integrated circuit, and at least two conductive patterns being formed between the driving integrated circuit and the main gamma compensating signal line, for utilizing the main gamma compensating voltage to apply at least two gamma compensating voltages to the driving integrated circuits.
The present invention may be further achieved in parts or in a whole by a display device comprising: a) a first substrate having a first prescribed dimension; b) a second substrate having a second prescribed dimension, the second substrate being placed in opposition to the first substrate and the first prescribed dimension being greater than the second prescribed dimension such that the second dimension defines a display area region, and a first side pad region being defined by boundaries of the first and second dimensions; c) a plurality of display cells formed on the display area region and between the first and second substrates; d) a plurality of first driving circuits formed on the first side pad region, the first driving circuits selecting corresponding display cells for displaying an image; and e) a compensation circuit formed on the first side pad region, the compensation circuit having: (1) a first conductive line for receiving a first compensation voltage, and (2) a plurality of conductive patterns, each conductive pattern being coupled to the first conductive line and a corresponding first driving circuit, wherein each conductive pattern includes: (i) a plurality of connection nodes coupled to the corresponding first driving circuit, and (ii) a plurality of second conductive lines, the plurality of second conductive lines coupling the plurality of connection nodes in series to the first conductive line such that a plurality of second compensation voltages, which are different from each other, are provide at the plurality of connection nodes, respectively.
The present invention can be also achieved in parts or in a whole by a layout pattern for compensating gamma characteristic of a liquid crystal display panel, comprising: (a) a first conductive line for receiving a first compensation voltage; and (b) a plurality of conductive patterns coupled to the first conductive line, wherein each conductive pattern includes: a plurality of connection nodes, and a plurality of second conductive lines, the plurality of second conductive lines coupling the plurality of connection nodes in series to the first conductive line such that a plurality of second compensation voltages, which are different from each other, are provide at the plurality of connection nodes, respectively.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.